The floor is arithmetic. If your all-in cost per mile is $1.80 and a 600-mile load needs 90 miles of deadhead, the load runs 690 miles and has to earn more than $1,242 just to break even. Anything below that loses money no matter how the rate per mile looks.
Above the floor, the lane sets the price. A load into a region where backhauls are easy is worth more to you than an identical load into a dead end. A receiver known for four-hour dwell is worth less than one that turns trucks in an hour. Reefer and flatbed carry commodity and securement risk that dry van does not.
Then read the market. Spot rates on the lane, the direction of freight flow, and the day of week all move the number. A truck that is already empty at the dock has less pricing power than one being booked two days out.
Finally, price the extras separately and put them on the rate confirmation: detention terms, layover, stop-offs, tarping, lumper reimbursement. A thin linehaul can still be a profitable load if the accessorials are billed and collected.
Terms in this answer: Cost Per Mile, Deadhead, Linehaul, Accessorial Charge, Spot Rate
In Trailflow: dispatch.